X-ray transformer control



i 'aten ted July 26 1949 UNITED STATES PATENT OFFICER X-RAY TRANSFORMER CONTROL Edwin Russell Goldfield, University Heights, Ohio, assignor to Picker X-Ray Corporation, Waite Manufacturing Division, Inc., Cleveland, Ohio, a corporation of Ohio Application December 23, 1946, Serial No. 717,890

8 Claims.

This invention relates to improvements in X-ray transformer controls and more particularly to a means for securing optimum transformer conditions for two separate X-ray tubes havin different kilovoltage ratings.

The need for my invention is apparent in X-ray tube systems utilizing one tube for superficial therapy at 140 kv., and another tube for radiography at ratings running up to 110 kv. It is a recognized fact that the transformer performance is very largely governed by the reactance of the winding more than anything else. This reactance might be expressed as a function of the coupling of the copper to the iron circuit and also as a function of the square of the number of turns. Obviously then, the best way to secure good performance is to reduce the turns and crowd the iron as tightly as possible against the copper. Since the proximity of the copper to the iron is dependent on the top voltage in the secondary of the transformer, one can get better coupling of copper to iron at 110 kv. than one can at 140 kv. Likewise, the secondary turns may be reduced in direct proportion. Heretofore, in X-ray systems of the type discussed herein, the optimum transformer design for radiographic work has been compromised in order to secure sufiicient voltage for superficial therapy. It is an object of the present invention to do away with these conditions so as to provide very advantageous transformer conditions for both radiography and superficial therapy.

Another object of the present invention is to provide a control of the Monitor type wherein a single control member operates selectively upon diiferent decks to simultaneously set up predetermined conditions for the X-ray operation to be performed. For instance, at the time that the 110 kv. X-ray tube is selected for radiography, it is customary to select the proper filament current for the X-ray tube, change the valve tube temperature, connect in a suitable timer, and in general, to change all of the factors in the control circuits to those which are suitable for radiography. In the same way, another setting of the Monitor control will select other values of the above-mentioned factors suitable for use in connection with superficial therapy use of the 140 kv. X-ray tube. The present invention comprises means operated automatically upon the selection'of suitable control circuits for radiography or for therapy, to select at the same time proper transformer conditions whereby optimum results will be secured whatever the voltage used.

Other objects of the invention include novel means arranged to carry out the above described purposes which will be clearly understood from the accompanying drawing and specification and the essential features of which will be set forth in the appended claims.

The drawing shows a diagrammatic View of electrical circuits and associated apparatus showing one embodiment'of my invention.

In the drawing, I have shown an X-ray tube H] for use under radiographic conditions up to kv. A second X-ray tube II is suitable for superficial therapy at kv. Suitable means is provided for energizing these tubes including high tension transformer means I2 and a fourvalve rectifier circuit l3 shown diagrammatically for simplicity. The high tension alternating current is fed to the rectifier circuit through lines 76 and TI. The rectified current is fed to the X-ray tube anode through line 18 and switch 46, and to the tube filament through lines 19 and 80 and switch 48.

Filament current for the X-ray tubes is supplied through filament transformer l4 which is a two-part transformer having one part l4a for providing a smaller focal spot in connection with therapy, and a second portion [41) for operating a larger focal spot in connection with radio raphy. The secondary Mat is connected to the tube filament by line 8| and switch 41, and by lines 82 and 30 and switch 48. The secondary M12 is connected to the tubefilament by line 83 and switch 49, and by lines 82 and 80 and switch 48. The primary current for the filament transformer is supplied from Ll, L2, through a milliammeter limiting resistance l5 located on one deck of the Monitor control system and through a focal spot selective switch It located on another deck of' the Monitor system. For simplicity, I have shown a control knob I! for manipulating a shaft I8 which extends to various decks of the Monitor system, only four of which are shown, but the use of which is familiar to those skilled in this art. In the position shown in the drawing, the switch arm I511 on one deck is in a position corresponding to the position of switch arm It on the other deck. In the position shown in full lines, the Monitor is set for radiography. The switch 16 is set to energize the portion Mb of the filament transformer so as to supply the large focal spot of the X-raytube. The switch [5a at the same time selects the proper milliammeter limiting resist: ance for this operation.

At the same time, the arm I9 on another deck 3 of the Monitor control is in contact with one of the control buttons for selecting a suitable timer for radiography. As shown in the lower portion of the diagram, this timer circuit receives its power from a low voltage source L3, L4, through line 2|, arm 59, buttons 20 and line 22, through -lines- 23and 24 tosenergize the timer motor 25', and then through lines 25, 27, and 23, back to L4. At the same time, another circuit leads from line 23 through line 29, radiography.

push button 39, line St, the winding of solenoid 32, relay 33 and line 34, back to lines Hand 28 to complete the circuit. Another circuit from line 22 leads through line 35, normally closed switch 36 to the normallyopen-switchs? which is controlled by relay 33. When both switches 36 and 31 are closed, a circuit is completed through line 38, relay 39 and line 28, back to the other side of the line.

ergizedtocause an exposure. The switch 40 is inithe circuit running from the electrical source L5, L6; through suitable connections later described, for energizing the primary of transformer. 12c Returning to the radiographic timer, when motor 25 is running, it drives a portion Ma of a clutch mechanismshown diagrammatically. This clutch mechanism drives a part 41b which in turn carries an arm 42-adaptedto open switch:35 when the timer has run a predeter- .mined distance. The position of the clutch is controlled by the armature 32a of the solenoid having'thewinding 32; The action is such that "the-clutch isnorinally released except when the relay winding 32 is. energized upon closin of the button 33; This starts the rotation of the part 411) which carries the timing arm42. At the same time, relay 33 is energized and closes switch 3'1 so as'to start an exposure. When the exposure is completed for the'timeset;'the" arm -4 2:opens-switch 3B stoppin the exposure.

When the Monitor is set in the position shown in the drawing, I have arrangeda fourth switch-arm for controlling the connection-of the various operating circuits to either tube l0 5 or corresponding to the various control circuitsselectedby the arms l5a, l5, l9 (and any other controllinggarmsconnected with'thePMon? .itor system). This-switcharm 43 controls-the operation of an electrical device such as the motor indicated diagrammatically at t; which turns a shaft 45movable withwhich is a switch 43 for connecting the anodeot one or the other of the X-ray tubes, switches 31, 48- and49 for connecting the cathode of one or the other vof the X-ray tithes, switches 5il-and-5lfor making acertain transformer secondary connection as will later appear, andswitch 52 for making a certain transformer primary connection as will later appear. The operating circuit for the switch controlling motor is fromthe electricalssource L3-through 1ine--53,m0tor. 44, line 5.4, switch 55,- which in the full line position completes a circuit through 1ines'56' andi'l toi'button 4311 which cooperates with switch arm :43 to complete a circuitthrough line 58-to thesource L4. In its dot-dash position, the switch completes a circuit through line-59 to one of the buttons 431) which coacts with switch arm 43.

to complete the circuit to the-source L5. Movable with shaft 45 is agenerally send-circular cam 6.0 which in the. full line position permits the closure of switch 55 .(hy means-not shown). to the full line position of the drawing. -When the motor 44 has rotated shait 45-thr0l1ghl80 The relay 39cont1ols switch 48 which closes-when the relay 39 is enp.

degrees the cam 60 takes the dot-dash position indicated in the drawing, which moves switch 55 from the full line position to the dot-dash position indicated. Another switch 6| provides a connection from line 56 through line 62 to line 59. A cam 63 movable with shaft 45 opens .switch fil; upon: each revolution. of shaft 45 through-degrees. Means not shown is provided for normally closing switch 6| when permitted by cam 63. The operation of this portion oftheapparatus should now be apparent. When the switch arm 43 is in the full line position shownin the drawing, the switch 55 is also in the full line position, and the motor operating circuit'is open -in=hoth places, namely, at switch 51 andat linetflfi However, when switch arm 43rislmoved toathe.dot-dash position indicated on the drawing, the circuit from motor 44 is completed-"through lines 51 and 58, switch 55 and line 54. The motor then starts to turn causing cam Elite move. to the 'dot-dashvposition indicated, so as-to move switch55 to thedot-dash position shownfin the drawing. Switohti closes during a: portion of. a/half cyclezandopens switch 6| at the proper time to stop the cam 50in its dot-dash position. Ghviously, as long as switch arm' 43: remains in its :dot-vdash position, the motor circuit through lines ST and 5.6. is open. Upon the return oiiswitchaarm 43% its full line position, the-circuit for motor- 44. then becomes closed through 1ines 59;'and"64,.switch55 (in its dot-dash-position) andline'54; Thereupon, another half cyclerof motor Mi occurs returning the parts-to the full line-position indicated in the drawing.

I provide a novel high tension transformer to cooperate with. the mechanism and circuits, thus far described.- Ihetran-sformer primary 2a:is always connected: by -line.-55 with the-source L5 andris connected bylinett-withthe source L6 whenever the exposure :switch :40 is closed. The transformer secondary- 12b with its central ground .61. is: always :utilized" whether tube 1 0-01 tube iiiszoperated. The transformer. primaries I20 and lzeare energized only when tube ill is operated, as willlpresently-ahp ar, and theircorresponding secondaries -l 2rZ-and l2 respectively, are in series with the secondary 12b through lines Strand Bil-whenever tube l-l.is;operated,.as will presently-ap ear, ,whereaathesecondary12d is shunted throughlines lily-and 114 wheneyertube I 0 is operated andthe transformer secondary =12) is shuntedthrough lines J 2=.and=13 whenever tube .1 ll. is operated; The switchesfifl sand-5i, previous- .ly. referred.-to,- are in -.the.- full line position when tube in isoperated, atewhich time, they closethe circuits 12', 13-and4fl, II, respectively, to-complate the shunts mentionedaabo e; When the switchesfifl audit are inithenotedash position corresponding: tothe; operationor tube H: the shunts-are openiandthe secondaries A 2d and i2f are-inseries with the secondariesl2b. for; the higher voltage operation. The primaries, 1 2c and me are energized from. the source L5 through line .14, switch 52. in its dot-dash position and line 15, bothz circuitsrheing completed through line 86 to the source L6.

When the Monitor knob. t-l-is turned to .place the switchiarms on-the variousdeeksin-zthe dotdashposition :the.drawing, thedeviceis-set for therapy using the X-raytuherll. At this time theswi-tch armdfi set :to energize the; primary of the filament transformer. portion 11a; which corresponds to -the smaller. 'focaliuspot. At the same time, more of the resistance l52i -llii i1li70 the circuit by the switch arm 15a. The operation of the switch arm 43 when turned to contact the button 43a has already been described and results in moving all of the switches connected with shaft. 45 to the dot-dash positions indicated. As pointed out in the preceding paragraph; this includes the energization of the high tension transformer primaries I20 and He through the movement of the switch arm 52. It also results in the opening of the shunts around the transformer secondaries [2d and Hi so that all of the transformer secondaries l2b, l2d and 12 are in series to provide the higher voltage utilized in connection with X-ray tube I l. V

When the switch arm I9 is moved to its dotdash position it selects a different timer especially adapted for therapy. Button 20a is connected through line 84 with switch '85 which initiates the therapy exposure. When this switch is closed, it completes one circuit through line -86, motor 81 and lines 88, and 58, back to the source L4. At the same time, another circuit is completed through line 89, switch 90 and lines 9|, 38, relay 39 and line 28 back to the source. Thus, when switch 85 is closed, it energizes relay 39 to close switch 40, starting an exposure. At the same time, motor 8'! starts to turn and at the end of a predetermined time, this causes the arm 81a to open switch 99 thus terminating the exposure.

It will be seen from the above description that I have provided apparatus and circuits whereby when a single master control, such as the Monitor system described, is turned to a position for radiography it automatically selects the various control circuits suitable for that operation, "and at the same time connects the tube H) in its energizing circuit and selects the transformer secondary [2b for the radiographic operation. On the other hand, when the Monitor is turned to a position corresponding to a superficial therapy operation the requisite control circuits for therapy are connected, the switches on shaft 45 are placed in contact with tube II to energize the same for therapy and the transformer secondaries [2d and I2 are automatically placed in series with the secondary IZb to supply the higher kilovolta-ge necessary for the opera-tion of tube I I. It results from this construction that it is possible to construct the transformer secondaries I 2d and I2) specially for high efficiency at the higher kilovoltages used for therapy inasmuch as these secondaries are only used at the higher voltages. I am thus enabled to obtain optimum transformer conditions both under radiographic and therapy conditions.

What I claim is:

1. In X-ray apparatus comprising two separate X-ray tubes the second of which has a higher anode kilovoltage requirement than the first, operating means for said tubes including high tension transformer means for energizing the anode to cathode circuits of said X-ray tubes, said transformer means having a plurality of secondaries, control means for said apparatus having at least two positions, control circuits for said first tube only and .operatively connected so as to be rendered operative by movement of said control means to one position, said control circuits also including one of said secondaries, control circuits for said second tube only and operatively connected so as to be rendered operative by movement of said control means to another position, and said last named control circuits including another of said secondaries.

2. In X-ray apparatus comprising two separate X-ray tubes the second of which has a higher kilovoltage requirement than the first, operating means for said tubes including high tension transformer means for energizing said X-ray tubes, said transformer means having a plurality of primaries with corresponding secondaries, control means for said apparatus having at least two positions, control circuits for said first tube only and operatively connected so as to be rendered operative by movement of said control means to one position, said control circuits also including one of said secondaries, control circuits for said second tube only and operatively connectedso as to be rendered operative by movement of said control means to another position, said last named control circuits includin circuits for connecting another of said secondaries in series with said one secondary and for causing energization of the primary for said other secondary, and said first namedcontrol circuits including means for shunting said other secondary and for causing deenergization of the primary for said other secondary.

3. In. X-ray apparatus comprising two separate X-ray tubes one of which is operable at a higher anode kilovoltage than the other, operating means for. selectively operating one orthe other of said tubes including high tension transformer means connectable in circuit for energizing one or the other of the anode to cathode circuits of said X-ray tubes, said transformer means having. a plurality of secondaries, at least one of said secondaries having characteristics adapted specially for use at said higher kilovoltage, and switch means for connecting said one secondary in a selected one of said tube energizing circuits only when said tube operable at higher kilovoltage is in said circuit.

4. In X-ray apparatus comprising two separate X-ray tubes one of which is operable at a higher anode kilovoltage than the other, operating means for said tubes including high tension transformer means selectively connectable in circuits for energizing the anode to cathode circuits of said X-ray tubes, said transformer means having a plurality of secondaries, at least one of said secondaries having characteristics adapted specially for use at said higher kilovoltage, switch means for connecting another of said secondaries in said tube energizing circuit for each of said tubes, and second switch means for connecting said one secondary in series with said other secondary only when said tube operable at higher kilovoltage is in said circuit.

5. The combination of claim 4 including a circuit providing a shunt around said one secondary and connecting said other secondary directly into said tube energizing circuit, and said switch means including switches for selecting for energization said tube of lower kilovoltage rating and other switches operable in unison with said first named switches for completing said shunt circuit.

6. The combination of claim 4 including a circuit providing a shunt around said one secondary and connecting said other secondary directly into said tube energizing circuit, a primary controlling said one secondary, a circuit for energizing said primary, and said switch means including switches for selecting for energization said tube of lower kilovoltage rating and other switches operable in unison with said first named switches for completing said shunt circuit and for breaking said primary energizing circuit.

'7. In X-ray apparatus comprising a higher voltage X-ray tube and a lower voltage X-ray tube, operating meansior said tubes including specialized control circuits for each of said tubes, master controlmeans having afirst pcsition opcratively connecting said "circuits for said tube of lower voltage vand having a second position operatively'connecting saidlcircuits tier said tube of higher voltage, electrically-operable switch control means having first andsecond positions, switches operatively connecting said operating means with said lower andihigher'voltage tubes respectivel when said switch control means is in first and second positions, an electrical circuit for energizing vsaidvswitch control means,

said last named circuitahaving first switch means responsive to said master control means and having second switch means responsive to said switch control means, said second switch means being :movable between first'and secondrpositions corresponding to said first and second positions of said switch control means, means operative by saidrswitch control zmea'nsforiso moving said second switch means, said second switchlmeans in first position completing said. electrical circuit .for energizing said switch control means when said firstswitch means-is in second position, said second switch means in second position completing said electrical circuitior energizingisaid switch control means whensaid first switch means is in first position, .andlmeans for automatically stopping 'sailiswitch control means whenitflhas moved trom'first to second position or vice versa.

.8. In X-ray apparatus comprising an X-ray tube for radiographyand an X-ray tube for therapy, electrical energizing circuits 'for each of one or its. positions to the other and to then stop, and said last named means having two energizing settings,. one setting including said switch control means in therapy position and said master control in radiography position, the other setting including said switch'control means in radiography position and said master control in therapy. position; whereby upon completing zeither'a therapy-or radiography operation, turning of the master control to a position to select the other operation automatically causes said'last named means to operate said switch control means through one cycle to move said energizin swi-tchmeans.

EDWIN RUSSELL GOLDFIELD.

REFERENCES CITED The: following references are of record in the file of this patent:

' UNIT-ED STATES PATENTS 

